1. Field of the Invention
This invention relates to a device for dispensing sealant.
2. Background Information
The use of sealing materials to fill voids in various kinds of constructions is widely known, especially in building construction. These sealing materials, also known as sealants, are used to keep undesirable environments in there proper place, such as rain, wind, or heat on the outside of buildings. These sealants are applied in a variety of forms and from a variety of apparatuses. The apparatuses used by large building construction companies or users of sealants, such as in the manufacture of appliances or automobiles, to dispense sealant materials into voids, may be very sophisticated and expensive. For many applicators of sealants, the use of a simple caulking gun to dispense sealants is the method of choice. As the use of sealants increased, the packaging for these materials changed and over several years, cartridges were the primary way to package sealant. The cartridges were most often designed with a nozzle through which a sealant composition could be extruded into a void or location requiring sealing. These cartridges were adapted to be loaded into devices equipped with mechanisms to push the sealant composition out of the cartridge package. Such devices are commonly called caulking guns or dispensing guns. These cartridges, depending on the kind of storage required for the sealant composition, were made from paper, foiled lined paper, plastic, and various kinds of molded and laminated constructions. A conventional sealant cartridge for sealants which cure by exposure to moisture, thus requiring protection from moisture during storage, is a single integrally molded cylindrical body having a nozzle which is used as an exit orifice and a plunger is disposed within the cylindrical body. Sealant composition is contained in a cavity defined by the face of the plunger in the discharge direction and the inner wall of the molded cartridge. The sealant composition is discharged through the exit orifice upon application of a force to the plunger by an extrusion device employing mechanical or pneumatic means. After as much of the sealant composition as possible is discharged from cartridge, it is discarded. These cartridges are discarded in landfills which is environmentally undesirable because the volume of the cartridge is large. To reduce the amount of waste caused by the disposal of the cartridges, the manufacturers of the sealant compositions and packages developed so called "sausage packages" for the sealant compositions. These sausage packages use much less material for the package, produce low amounts of solid waste, and can be made air and moisture impermeable, so that they can contain sealant composition which is sensitive to moisture. These sealant containing sausage packages can be inserted into some kinds of dispensing cartridges or caulking gun barrels which permits discharge of sealant composition. The waste created by the spent sausage skin is considerably lower than that created by the discard of the cartridges. However, although the amount of package waste may be reduced, the dispensing devices need to be cleaned each time a different color sealant is used or before it is set aside until required for the next use, such as overnight.
Sealant dispensers which are adapted for use with the sausage package comprise a gun barrel with a nozzle assembly forming an integral part of the barrel, or releasably attached to the barrel with suitable securing means, a piston disposed within the barrel and mechanical or pneumatic means for actuating the piston located at the opposite end of the barrel which is operated using a trigger mechanism.
Salmon in French Patent No. 930,316, granted Aug. 4, 1947 and published Jan. 22, 1948, to Expandite Products, Limited teaches a process and device for applying a composition in a seam or in a fissure. A caulking compound is hermetically sealed in a cylindrical section of a package. The material for the package is preferably a transparent sheet of cellulose acetate. One end of the package is cut by scissors so as to allow the caulking compound to be forced by a plunger of a caulking pistol through an orifice. The end of the package may be cut either before or after introducing the package charge into the pistol barrel. After forcing the charge of the pistol through the open end of the package while at the same time leaving the package in the barrel, the packaging is removed from the barrel by removing a cap and destroying it and introducing a new charge. The pistol nozzle is attached to a cap concave on the inside which covers the end of the barrel and the end of the pistol plunger is convex so as to have a surface complimentary to the concave surface of the cap so as to assure integral expulsion of the packaging composition. The device described by Salmon would be difficult to change kinds of sealants without substantial effort to clean the pistol barrel and nozzle when different kinds of sealant composition are used sequentially.
Seng in French Patent No. 1,127,069, granted on Aug. 6, 1956, and published on Dec. 7, 1956, teaches a distributor for viscous products such as greases and plastic products which can be polymerized cold before their polymerization. The distributor includes a cylindrical body sealed by a threaded cover and by a threaded piece to which the distribution adjustment is attached. Inside a body, a piston is mounted which is one piece with a rod equipped with a handle and this piston moves in this body under the effect of a spring. The piston can be kept in place when it encounters the effect of a spring by means of a jam lever which may penetrate into a cover through an opening which acts on the point of articulation and which is equipped with a drilled hole through which the rod passes with a lever being jammed obliquely onto this rod by means of the spring. The piston rod has an extension which projects from the outer side of the piston and against which a collar equipped with bosses can be kept by means of a screw. A sealing piece is also equipped with an external cylindrical throat which causes there to be a cylindrical recess with the internal wall of the body. A sack containing viscous product is placed into a cavity of the distributor and jerking movement is supplied by means of the jamming device which acts against the piston rod and which releases this rod under the effect of the operator's hand. The viscous material is contained in a casing in the form of a sack placed into the distributor body after removing the distribution adjustment and which is open after this installation. The piston is then one piece with a prominent collar equipped with vents which communicate with the back of the piston by means of holes made in this latter and which rests on the bottom of this casing. This distributor is a complicated device and not suitable for multiple kinds of product without extensive clean up.
A sealant dispensing cartridge on the market which employs sealant sausage packages comprises a self supporting cylindrical sleeve, an end cap and a plunger disposed within the sleeve, the plunger, inner wall of the sleeve and the end cap provide a cavity for the sealant sausage package. The sleeve is adapted at one end to releasably receive the end cap. The main body of the plunger comprises a cylindrical surface in sliding contact with the inner wall of the sleeve and faces, one of which is substantially flat against which force is brought to bear from a gun mechanism, the other face, in the discharge direction provides attachment means for fixing thereto a pressure relief spring which comprises a disc with diametrically opposed tongues, slightly larger in diameter than the main body of the plunger and is in frictional engagement with the inner wall of the sleeve. A plurality of holes run through the main body of plunger and the pressure release disc thus creating a pressure equalizing effect as the plunger is driven along the sleeve.
Extrusion devices employing such a cartridge generally comprise a framework in which the cartridge is supported and means for supplying a force to the plunger such as a piston which is actuated by mechanical means using a trigger mechanism, for example a skeleton gun.
Segatz in U.S. Pat. No. 4,840,293, issued Jun. 20, 1989, assigned to ARA-Werk Kramer GmbH & Co. describes an apparatus for discharging a bead or strand of pasty material from a deformable tubular container such as a tubular bag having a bag-loadable cylinder with a front face pointing in a discharge direction, the front face having a central opening aligned with a nozzle connection of the tubular bag. A substantially piston-like pressure member is axially displaceable against the tubular bag in the cylinder. In order to avoid drooling and dribbling of material through the nozzle after interruption of the discharge process and also to prevent jamming of the edges of the tubular bag, the pressure member has a pressure relief spring supported on the wall of the cylinder and cooperating therewith, the spring having spring tongues directed obliquely forward around the deformable bag. The apparatus is used to extrude sealant material encapsulated in a sausage package and comprises the cylinder adapted to receive the sausage package and a plunger which is provided with a pressure release spring attached to one face. The specification states that where pneumatic means are provided for moving the plunger, an elastic closure having a diameter slightly larger than the diameter of the main body of the plunger should be provided to seal the plunger against the inner surface of the cylinder. The elastic closure is attached to a face of the plunger opposing the face connecting the pressure release spring. While this apparatus is satisfactory in many respects, it is unsuitable for use in both mechanically operated and pneumatic extrusion devices without necessary modification of the plunger. Such modification requires the dismantling and reassembly of the apparatus, a time consuming process which is an inconvenience to an operator.